com.github.tonivade.purefun.optics.Prism Maven / Gradle / Ivy

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/*
 * Copyright (c) 2018-2019, Antonio Gabriel Muñoz Conejo 
 * Distributed under the terms of the MIT License
 */
package com.github.tonivade.purefun.optics;

import static com.github.tonivade.purefun.Producer.cons;
import static java.util.Objects.requireNonNull;

import com.github.tonivade.purefun.Function1;
import com.github.tonivade.purefun.Operator1;
import com.github.tonivade.purefun.type.Either;
import com.github.tonivade.purefun.type.Option;

public final class Prism {

  private final Function1> getOption;
  private final Function1 reverseGet;

  private Prism(Function1> getOption, Function1 reverseGet) {
    this.getOption = requireNonNull(getOption);
    this.reverseGet = requireNonNull(reverseGet);
  }

  public static  Prism of(Function1> getOption, Function1 reverseGet) {
    return new Prism<>(getOption, reverseGet);
  }

  public Option getOption(T target) {
    return getOption.apply(target);
  }

  public T reverseGet(R value) {
    return reverseGet.apply(value);
  }

  public Either getOrModify(T target) {
    return getOption(target).fold(cons(Either.left(target)), Either::right);
  }

  public Operator1 modify(Operator1 mapper) {
    return target -> modifyOption(mapper).apply(target).getOrElse(target);
  }

  public Operator1 set(R value) {
    return modify(ignore -> value);
  }

  public Function1> modifyOption(Operator1 mapper) {
    return target -> getOption(target).map(mapper).map(reverseGet);
  }

  public Function1> setOption(R value) {
    return modifyOption(ignore -> value);
  }

  public  Prism compose(Prism other) {
    return new Prism<>(
        target -> this.getOption(target).flatMap(other::getOption),
        value -> this.reverseGet(other.reverseGet(value)));
  }
}